Bibliographic record
Abstract
Abstract This paper investigates the feasibility of bitumen production using SAGD technology with a longer wellbore. A longer wellbore can be used to exploit a greater volume of reservoir with a single well as opposed to multiple wells, thus decreasing pad and drilling costs. The major concern of using a longer wellbore from a reservoir engineering point of view is the potentially ununiform steam chamber growth over the whole well length due to pressure drop in the horizontal wells. Reservoir simulation was performed using CMG STARS and Qflow to address the issue. The pressure drop inside the wellbore is calculated using Qflow. Reservoir simulations were performed using STARS. A sectioned model was constructed, dividing the whole length of the horizontal wellbore into multiple sections, each with its own pressure restriction to match the pressure drop obtained from Qflow. The results showed that with sufficiently large wellbore size that resulted in sufficiently low pressure drop, one longer well performed as well as two shorter wells. If the pressure drop in the wellbore is too large by using a smaller size wellbore, the production from a longer well can be significantly impeded. Introduction Since the discovery of oil sands, many techniques have been tried – and improved upon – to recover the highly viscous bitumen for energy consumption. One of the methods of bitumen recovery that is becoming increasingly prevalent is a thermal in-situ method called Steam Assisted Gravity Drainage (SAGD). Butler (1) first proposed this method in the late 1970s and it was field tested in AOSTRA's Underground Test Facility (UTF) in the 1980s. The initial phase of UTF testing produced successful field results (2, 3). Following Phase A, Phase B was started, implementing the use of longer horizontal wells (4, 5). Surface-operated SAGD was studied in Phase D (6). Following these successful pilot tests, a number of commercial projects have been developed, including Petro-Canada's MacKay River project. One of the factors that needs to be considered in commercial projects is the optimization of the horizontal well length. Usually, SAGD wells are 500 to 700 m long, horizontally. This paper will examine the effectiveness of using a longer horizontal wellbore in SAGD. There is tremendous potential for economic savings in implementing longer wells in a SAGD project. A longer well has the ability to reach greater lengths within a reservoir with one single well as opposed to multiple wells. When multiple wells are drilled, multiple pads must also be built – one for each group of wells. Thus, to cover a certain reservoir, the average pad cost will be lower for longer wells. Another significant cost advantage of the longer well is the fact that less riser sections (also known as build sections) need to be drilled and completed. The riser section has a significantly higher cost than the horizontal section because it is generally much larger in diameter. By decreasing the number of wells in a pattern with the use of longer wells, the cost of all the riser sections is decreased significantly.
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.001 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one teacher head, not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".